The QSX-85 shell-and-tube heat exchanger is suitable for process medium cooling or heating sections in the chemical, petroleum, pharmaceutical and other industries. The following lists the key points that technical engineers need to verify during model selection and site layout from the perspective of application scenarios.
The chemical name, mass flow rate or volume flow rate, inlet and outlet temperatures, working pressure and allowable pressure drop of the hot-side and cold-side media shall be recorded separately. The corrosiveness of the medium determines the material selection for the tube side and shell side; the flow rate and temperature difference affect the estimation of heat transfer area; and the allowable pressure drop constrains the baffle spacing and the number of tube passes.
The shell-and-tube heat exchanger requires axial space reserved for withdrawing the tube bundle, and maintenance space not less than the tube bundle length shall be reserved along the shell length direction. For horizontal installation, check the compatibility between the supports and the foundation anchor bolts; for vertical installation, calculate the effects of wind load and seismic load on the shell.
The orientation, diameter and flange standard of the hot-side and cold-side inlet and outlet nozzles shall be consistent with the on-site piping. Note the influence of whether the hot side flows through the tube side or the shell side on pressure drop and cleaning convenience; an impingement plate may be provided at the shell-side nozzle to reduce the erosion of the inlet medium on the tube bundle.
Actual working conditions often deviate, so after parameter confirmation, correction based on operating data is still required. During initial commissioning, the actual inlet and outlet temperatures, flow rate and pressure drop shall be recorded and compared with the design values; when the deviation is large, verify the assumed values of the heat transfer coefficient and fouling thermal resistance.
Determine the corrosion allowance of the tube bundle and shell according to the corrosiveness of the medium. For working conditions requiring frequent cleaning, a removable tube bundle structure is preferable, and the influence of the cleaning liquid on the sealing gaskets and tube sheet connections shall be considered; the fixed tube sheet structure is suitable for occasions with small temperature differences and clean media.
